I think you're right about that, pork. The tree can't be all that unhappy if it's got enough jam to bloom.
Couple of things that might help it out, though - I'd move the crotons (shrubs with colored foliage) from around there, at least a few feet further away. Competition for water and nutrients right in the root zone isn't helping it at all.
The marble chip mulch (white rocks) leaches calcium into the soil and raises the pH which can make acid-loving plants like magnolia starve slowly. They really like a more acidic soil in general. So if you can manage to remove as much as possible of the marble chips, and replace the mulch with something like wood chips that will also help the magnolia to be happier.
